The purpose of this research is to investigate the role of social, psychological and genetic factors that previous research and theory suggest may be important in the etiology of the main types of psychopathology that are inversely related to social class -- schizophernia, major depression, anti-social personality, substance abuse, and a type of nonspecific psychological distress that we are terming "demoralization." The framework for the study is provided by a quasi-experimental strategy designed to investigate the social causation-social selection issue posed by the class differences. The strategy involves comparisons of rates of each type of psychopathology in advantaged and disadvantaged ethnic groups with class controlled, and tests of related predictions about the presence of severe environmentally induced stress and the presence of the psychopathology in first degree relatives of cases by contrast with controls. Israel is the research setting. There are two main reasons for this choice: First the quasi-experimental strategy requires an open society in which ethnic assimilation is taking place. Second, study of the processes involved and their consequences can best be accomplished when a well kept Population Register and Psychiatric Register are available. Israel, probably uniquely, meets both sets of requirements. In Israel, relatively disadvantaged North African and Asian Jews will be compared with relatively advantaged Jews of European origin. Main focus will be on a probability sample of about 5000 men and women born in Israel between 1948 and 1952; a subsample of 750 cases and controls from this cohort; and about 2,800 first degree relatives of these cases and controls. The instruments for identifying diagnosing cases consist of brief screening scales from the Psychiatric Epidemiology Research Interview (PERI) based on our methodological research over the past 10 years and the Endicott and Spitzer's Schedule for Affective Disorders and Schizophrenia.